Datasheet

Section 6 Bus Controller (BSC)
Page 202 of 1408 R01UH0309EJ0500 Rev. 5.00
Sep 24, 2012
H8S/2456, H8S/2456R, H8S/2454 Group
(4) 16-Bit, 3-State Access Space
Figures 6.15 to 6.17 show bus timings for a 16-bit, 3-state access space. When a 16-bit access
space is accessed, the upper half (D15 to D8) of the data bus is used for even addresses, and the
lower half (D7 to D0) for odd addresses. Wait states can be inserted.
Bus cycle
T
1
T
2
Address bus
φ
CSn
AS
RD
D15 to D8
Valid
D7 to D0
Invalid
Read
HWR
LWR
D15 to D8
Valid
D7 to D0
Write
High
T
3
High impedance
Notes: 1. n = 0 to 7
2. When RDNn = 0
Figure 6.15 Bus Timing for 16-Bit, 3-State Access Space
(Even Address Byte Access)